Hydrea (Hydroxycarbamide)
Cytostatic medication for chronic leukemia and myeloproliferative disorders
Hydrea (hydroxycarbamide, also known as hydroxyurea) is a cytostatic medication that inhibits cell division in rapidly dividing cells, particularly cancer cells. It is primarily prescribed for chronic myeloid leukemia (CML) and other myeloproliferative disorders. This comprehensive guide covers everything patients need to know about Hydrea, including its uses, correct dosage, potential side effects, drug interactions, and important safety information. All information is based on international medical guidelines and reviewed by specialist physicians.
Quick Facts
Key Takeaways
- Hydrea (hydroxycarbamide) is a cytostatic drug that works by inhibiting DNA synthesis in rapidly dividing cells, effectively slowing cancer cell growth.
- It is primarily used for chronic myeloid leukemia (CML), essential thrombocythemia, polycythemia vera, and other myeloproliferative disorders.
- Regular blood tests are essential during treatment to monitor bone marrow function, as the most common serious side effect is bone marrow suppression.
- Hydrea must not be used during pregnancy or breastfeeding. Both men and women must use effective contraception during and after treatment.
- Capsules should be handled with care (cytotoxic agent) and swallowed whole without opening, crushing, or chewing.
What Is Hydrea and What Is It Used For?
Hydrea contains the active substance hydroxycarbamide (also known internationally as hydroxyurea), which belongs to the class of antineoplastic agents. These are medications specifically designed to interfere with the growth and spread of cancer cells in the body. Hydroxycarbamide works by inhibiting the enzyme ribonucleoside diphosphate reductase, a critical enzyme in the DNA synthesis pathway. By blocking this enzyme, the drug prevents the conversion of ribonucleotides to deoxyribonucleotides, which are the building blocks needed for DNA replication. This disruption of DNA synthesis is particularly effective against rapidly dividing cells, as cancer cells typically divide much faster than normal cells.
The primary indication for Hydrea is chronic myeloid leukemia (CML), a type of blood cancer that originates in the bone marrow and leads to the overproduction of white blood cells. In CML, the medication helps control the abnormally high white blood cell count and can reduce symptoms such as fatigue, weight loss, and an enlarged spleen. Hydrea is also used in other myeloproliferative disorders, including essential thrombocythemia (excessive platelet production), polycythemia vera (overproduction of red blood cells), and myelofibrosis (scarring of the bone marrow).
Beyond its oncological applications, hydroxycarbamide has become an important treatment in the management of sickle cell disease. In this context, the drug works by increasing the production of fetal hemoglobin (HbF), which reduces the sickling of red blood cells and decreases the frequency of painful vaso-occlusive crises. The World Health Organization (WHO) includes hydroxycarbamide on its Model List of Essential Medicines for the treatment of sickle cell disease, reflecting its importance in global healthcare.
It is worth noting that hydroxycarbamide may also be used for other conditions not specifically mentioned in this guide. Your prescribing physician will determine whether Hydrea is appropriate for your specific medical condition. Always follow the instructions and guidance of your healthcare provider regarding the use of this medication.
What Should You Know Before Taking Hydrea?
Before beginning treatment with Hydrea, your healthcare provider will conduct a thorough medical evaluation to ensure the medication is safe and appropriate for you. This assessment typically includes comprehensive blood tests to evaluate your bone marrow function, kidney function, and liver function. Understanding the precautions and contraindications is essential for safe use of this cytostatic medication.
Contraindications
If you are allergic (hypersensitive) to hydroxycarbamide or any of the other ingredients in this medicine (listed in the composition section below). An allergic reaction may include skin rash, itching, swelling of the face or throat, or difficulty breathing. If you experience any of these symptoms, seek immediate medical attention.
Warnings and Precautions
Talk to your doctor before taking Hydrea if any of the following apply to you:
- Impaired kidney function: Hydroxycarbamide is primarily excreted through the kidneys. If your kidneys are not functioning optimally, the drug may accumulate in your body, increasing the risk of side effects. Your doctor may need to adjust the dose or monitor your kidney function more frequently.
- Impaired liver function: Although hydroxycarbamide is not primarily metabolized in the liver, liver disease can affect your overall ability to tolerate the medication. Liver function tests should be monitored during treatment.
- Reduced bone marrow function: Since Hydrea works by suppressing rapidly dividing cells, it can significantly affect bone marrow function. Your doctor will determine your bone marrow status through blood tests before starting treatment. If your blood counts are already low, the dose may need to be reduced or treatment temporarily paused.
- Elderly patients: Older adults may be more sensitive to the effects of hydroxycarbamide, and lower doses may be required. Close monitoring is particularly important in this population.
- Vaccination plans: Live vaccines should not be administered during treatment with Hydrea, as the immunosuppressive effects of the drug may lead to an enhanced vaccine reaction or serious infection. Discuss all vaccination plans with your doctor before starting treatment.
- Previous radiation therapy: If you have received radiation therapy in the past, the combination with Hydrea may increase the risk of certain side effects, particularly skin reactions and bone marrow suppression.
- Current or recent interferon treatment: Combination therapy with interferon has been associated with an increased risk of severe skin reactions, including skin ulcers and tissue necrosis (death of skin tissue).
If you have diabetes and use a continuous glucose monitoring (CGM) system to measure your blood sugar, be aware that hydroxycarbamide may interfere with certain CGM devices and produce falsely elevated blood sugar readings. This could lead to taking more insulin than necessary, potentially causing dangerously low blood sugar (hypoglycemia). Speak with the doctor who prescribed your CGM about whether it is safe to use while taking Hydrea.
Secondary cancers: Long-term treatment with hydroxycarbamide has been associated with the development of secondary leukemia and skin cancer. During treatment and after it has ended, you should protect your skin from sunlight (using sunscreen, protective clothing, and avoiding excessive sun exposure) and regularly examine your skin for any changes or new growths. Your doctor will also perform regular skin examinations during follow-up visits.
Hemolytic anemia: If blood tests reveal hemolytic anemia (a condition in which red blood cells are destroyed faster than they are produced), your doctor will discontinue treatment with Hydrea.
Folic acid monitoring: Hydroxycarbamide treatment can sometimes mask a folic acid deficiency. Your doctor may recommend regular monitoring of your folic acid levels and may prescribe folic acid supplements if necessary.
Hydration: It is important to drink plenty of fluids during treatment with Hydrea to help your kidneys process the medication and its metabolites effectively.
Children and Adolescents
The safety and efficacy of Hydrea in children have not been fully established. Use in pediatric patients should only be considered under strict medical supervision and when the potential benefits outweigh the risks. In some countries, hydroxycarbamide is approved for use in children with sickle cell disease, but the dosing and monitoring protocols differ from adult use.
Pregnancy and Breastfeeding
Hydrea must not be used during pregnancy unless strictly prescribed by your doctor in exceptional circumstances. Hydroxycarbamide can cause birth defects and has been shown to be teratogenic (harmful to the developing fetus) in animal studies. Women of childbearing potential must use effective contraception during treatment and for at least 6 months after the last dose.
Breastfeeding: Hydrea must not be used during breastfeeding due to the risk of serious side effects in the nursing infant. If your doctor determines that treatment is necessary, breastfeeding must be discontinued before starting Hydrea.
Male fertility: Hydroxycarbamide may affect sperm production. Men should consider sperm banking (cryopreservation) before starting treatment. Effective contraception should be used during treatment and for at least 3 months after the last dose. Hydroxycarbamide may be genotoxic (damaging to DNA), which is another reason for strict contraceptive measures in both men and women.
Driving and Operating Machinery
You are responsible for assessing whether you are fit to drive or operate machinery while taking Hydrea. Some side effects of the medication, such as dizziness, drowsiness, or disorientation, may impair your ability to perform these activities safely. If you experience any such effects, avoid driving or operating machinery until you feel well enough to do so. Discuss any concerns with your doctor or pharmacist.
Important Information About Ingredients
Lactose: This medicine contains lactose. If you have been told by your doctor that you have an intolerance to some sugars, consult your doctor before taking this medicine.
Sodium: This medicine contains 11.67 mg sodium (the main component of table salt) per capsule, equivalent to approximately 0.6% of the WHO-recommended maximum daily intake of sodium for an adult.
How Does Hydrea Interact with Other Drugs?
Drug interactions are an important consideration when taking Hydrea. Hydroxycarbamide can interact with various other medications, potentially increasing the risk of side effects or affecting the efficacy of either drug. It is essential to inform your doctor or pharmacist about all medications you are taking, have recently taken, or might take, including over-the-counter medicines, vitamins, and herbal supplements.
Major Interactions
| Interacting Drug | Effect | Clinical Significance |
|---|---|---|
| Didanosine (ddI) | Increased risk of pancreatitis, hepatotoxicity, and peripheral neuropathy; cases have been fatal | Avoid combination; use alternative antiretroviral if possible |
| Stavudine (d4T) | Increased risk of pancreatitis, hepatotoxicity, and peripheral neuropathy; cases have been fatal | Avoid combination; use alternative antiretroviral if possible |
| Live vaccines | Increased risk of severe infection due to immunosuppression; enhanced vaccine side effects | Do not administer live vaccines during treatment |
| Other cytostatic agents | Increased risk of bone marrow suppression, infections, and other overlapping toxicities | Close blood count monitoring required; dose adjustments may be needed |
| Radiation therapy | Enhanced radiation toxicity, including skin reactions and bone marrow suppression | Enhanced monitoring; dose adjustment may be necessary |
Other Notable Interactions
| Interacting Drug | Effect | Recommendation |
|---|---|---|
| Allopurinol | Hydrea increases uric acid levels; allopurinol dose may need adjustment | Monitor uric acid levels; adjust dose of uric acid-lowering agent as needed |
| Interferon | Increased risk of severe skin ulcers and tissue necrosis | Avoid combination when possible; monitor skin carefully if used together |
| Other bone marrow-suppressing drugs | Additive bone marrow suppression | Frequent blood count monitoring; dose reduction may be needed |
The interactions listed above are not exhaustive. Hydroxycarbamide may interact with other medications not mentioned here. Always inform your healthcare provider about every medication, supplement, or herbal remedy you are using before starting treatment with Hydrea. Your doctor will evaluate potential interactions and make any necessary adjustments to your treatment plan.
What Is the Correct Dosage of Hydrea?
The dosage of Hydrea is always individually determined by your prescribing physician. The dose depends on several factors, including the type of condition being treated, your body weight or body surface area, your kidney and liver function, and your blood count results. Always take this medication exactly as your doctor has instructed. If you are unsure about your dose, consult your doctor or pharmacist.
Adults
Typical Adult Dosage
The usual starting dose for most indications ranges from 15 to 30 mg/kg body weight per day, taken as a single daily dose. For a 70 kg adult, this corresponds to approximately 1,000 to 2,000 mg (2 to 4 capsules) per day. Your doctor will adjust the dose based on your blood count results, typically monitoring weekly during the initial phase of treatment.
In some treatment protocols, an intermittent dosing schedule may be used, where a higher dose (e.g., 80 mg/kg) is given every third day. Your doctor will determine which dosing schedule is most appropriate for your condition.
Children
Pediatric Use
The safety and efficacy of Hydrea in children have not been fully established for most indications. When used in pediatric patients (e.g., for sickle cell disease in some jurisdictions), the dosage is carefully individualized by the treating physician based on the child's weight and clinical response. Pediatric use should only be under the supervision of a specialist experienced in treating the relevant condition.
Elderly Patients
Elderly Dosing
Elderly patients may be more susceptible to the effects of hydroxycarbamide, particularly bone marrow suppression. Lower starting doses are often recommended, with careful and frequent monitoring of blood counts, kidney function, and liver function. Dose adjustments should be made based on the patient's individual response and tolerability.
How to Take Hydrea
- Swallow capsules whole with a glass of water. Do not open, crush, or chew the capsules.
- The capsules can generally be taken with or without food, but taking them at the same time each day helps maintain consistent drug levels.
- Handle Hydrea capsules with care, as they contain a cytotoxic substance. Keep them away from children and pets.
- Wash your hands with soap and water after every handling of the capsules, or wear protective gloves.
- If a capsule breaks or dissolves, wash your hands thoroughly with water immediately.
Missed Dose
If you forget to take a dose of Hydrea, do not take a double dose to compensate. Contact your doctor for advice on what to do if you have missed a dose. In general, take the next dose at the scheduled time unless your doctor instructs you otherwise.
Overdose
If you have taken too much Hydrea, or if a child has accidentally ingested the medication, contact your doctor, hospital emergency department, or poison control center immediately. Symptoms of overdose may include severe bone marrow suppression (extremely low blood cell counts), mouth sores, skin inflammation, and swelling of the hands and feet. Early medical intervention is critical.
What Are the Side Effects of Hydrea?
Like all medications, Hydrea can cause side effects, but not all patients will experience them. The severity and type of side effects can vary between individuals and depend on the dose, duration of treatment, and individual patient factors. Your doctor will monitor you closely during treatment to detect and manage any side effects early.
- Severe infection (fever, chills, sore throat) – may indicate dangerously low white blood cell count
- Unusual fatigue or paleness – may indicate severe anemia
- Unexplained bruising or bleeding – may indicate low platelet count
- Difficulty breathing – may indicate lung involvement
- Skin ulcers – may indicate cutaneous vasculitis (inflammation of blood vessels in the skin)
Very Common
May affect more than 1 in 10 people
- Bone marrow suppression (decreased blood cell production)
- Anemia (low red blood cells)
- Loss of appetite
- Nausea and vomiting
- Diarrhea
- Constipation
- Inflammation of the mouth lining (stomatitis)
- Stomach irritation and digestive discomfort
- Pancreatitis (inflammation of the pancreas; occasionally fatal)
- Skin rashes (macular, papular, and raised lesions)
- Hair loss (alopecia)
- Skin and subcutaneous inflammation
- Facial redness or redness on arms, legs, hands, and feet
- Skin peeling and pigmentation changes
- Skin and nail atrophy (thinning)
- Cutaneous vasculitis (inflammation of blood vessels in the skin) with skin ulcers
- Elevated uric acid levels (hyperuricemia)
- Elevated blood urea nitrogen (BUN)
- Elevated creatinine levels
- Difficulty urinating
- Decreased or absent sperm production
- Fever, chills
- Weakness and malaise (general feeling of illness)
Common
May affect up to 1 in 10 people
- Skin cancer
- Disorientation
- Hallucinations
- Seizures (convulsions)
- Dizziness
- Headache
- Peripheral neuropathy (nerve damage in hands and feet)
- Drowsiness
- Elevated liver enzymes
- Cholestasis (impaired bile flow)
- Hepatitis (liver inflammation)
- Liver damage (occasionally fatal)
- Lung toxicity (interstitial lung disease)
Rare
May affect up to 1 in 1,000 people
- Tumor lysis syndrome (abnormal blood values caused by rapid breakdown of tumor cells, which can lead to heart rhythm changes and impaired kidney function)
- Localized tissue necrosis (death) as a consequence of cutaneous vasculitis with ulceration, particularly in association with current or previous interferon treatment
Frequency Not Known
Cannot be estimated from available data
- Drug-induced fever (high fever with or without gastrointestinal, pulmonary, musculoskeletal, liver and biliary, skin, or cardiovascular symptoms; may occur weeks after starting treatment)
- Severe pulmonary disease (fever, cough, or breathing difficulties)
- Nail pigmentation (discolored nails)
- Dermatomyositis-like skin inflammation (red, scaly patches potentially with joint pain)
- Hemolytic anemia (red blood cells destroyed faster than produced)
It is important to report suspected side effects after the medicine has been authorized. This allows ongoing monitoring of the medicine's benefit-risk balance. Healthcare professionals and patients are encouraged to report any suspected adverse reactions to their national pharmacovigilance authority.
How Should You Store Hydrea?
Proper storage of Hydrea is important to maintain the medication's effectiveness and to prevent accidental exposure, particularly for children and pets. Since Hydrea contains a cytotoxic substance, special care must be taken to ensure safe handling and storage at all times.
- Temperature: Store at or below 25°C (77°F). Do not freeze the capsules.
- Light and moisture: Keep capsules in the original container with the lid tightly closed to protect from moisture.
- Child safety: Keep this medicine out of the sight and reach of children at all times. The capsules must be stored securely, as accidental ingestion by a child can be extremely dangerous.
- Expiry date: Do not use Hydrea after the expiry date printed on the label (EXP). The expiry date refers to the last day of the stated month.
- Disposal: Do not dispose of unused or expired medicines in household waste or down the drain. Return them to your pharmacy for safe disposal. This protects the environment and prevents accidental exposure.
What Does Hydrea Contain?
Understanding the full composition of Hydrea is important, particularly if you have known allergies or intolerances to any pharmaceutical ingredients. Below is a detailed breakdown of the active and inactive ingredients in each capsule.
Active Ingredient
Each hard capsule contains 500 mg hydroxycarbamide (also known as hydroxyurea). This is the pharmacologically active substance responsible for the therapeutic effects of the medication.
Inactive Ingredients (Excipients)
- Lactose monohydrate (42.2 mg per capsule)
- Anhydrous disodium phosphate
- Anhydrous citric acid
- Magnesium stearate
Capsule Shell
- Gelatin
- Erythrosine (E127)
- Indigo carmine (E132)
- Titanium dioxide (E171)
- Yellow iron oxide (E172)
Printing Ink
- Shellac
- Black iron oxide (E172)
- Propylene glycol (E1520)
- Concentrated ammonia (E527)
Appearance and Packaging
Hydrea 500 mg hard capsules are two-piece opaque gelatin capsules with a pink lower half and a green upper half. The capsules are printed with "CHP 500" in black ink. They are supplied in a glass bottle containing 100 capsules.
Marketing Authorization Holder: CHEPLAPHARM Arzneimittel GmbH, Ziegelhof 24, 17489 Greifswald, Germany.
Frequently Asked Questions About Hydrea
Hydrea (hydroxycarbamide) is a cytostatic medication primarily used to treat chronic myeloid leukemia (CML), essential thrombocythemia, polycythemia vera, and other myeloproliferative disorders. It works by inhibiting DNA synthesis in rapidly dividing cells, thereby slowing the growth of cancer cells. In some countries, it is also approved for sickle cell disease, where it reduces the frequency of painful crises by increasing fetal hemoglobin production.
The most common side effects (affecting more than 1 in 10 patients) include bone marrow suppression (leading to anemia, low white blood cell counts, and low platelet counts), nausea and vomiting, diarrhea, mouth sores, skin rashes, hair loss, nail and skin changes, and elevated uric acid levels. Regular blood tests are essential to monitor bone marrow function throughout treatment.
It is generally recommended to avoid or strictly limit alcohol consumption while taking Hydrea. Alcohol can place additional strain on the liver and may worsen side effects such as nausea, liver enzyme elevations, and bone marrow suppression. Discuss your alcohol consumption with your doctor, who can provide personalized advice based on your overall health and treatment plan.
Hydrea capsules contain a cytotoxic substance and should be handled with appropriate care. Always wash your hands with soap and water after handling the capsules, or wear protective gloves. If a capsule breaks open or dissolves, clean the area carefully and wash your hands thoroughly. Do not open, crush, or chew the capsules – swallow them whole with water. Keep capsules away from children and pets at all times.
Yes, Hydrea can significantly affect fertility in both men and women. In men, it may reduce or completely stop sperm production. Men should consider sperm cryopreservation (freezing) before starting treatment. Effective contraception must be used during treatment and for at least 3 months after the last dose for men, and at least 6 months for women. Hydroxycarbamide is teratogenic and can damage DNA, making it essential to avoid pregnancy during treatment.
Regular blood tests are critical during Hydrea treatment. A complete blood count (CBC) is typically performed weekly at the start of treatment to monitor white blood cells, red blood cells, and platelets. Once a stable dose is established, blood tests may be performed every 2 to 4 weeks. Additionally, kidney function tests (creatinine, BUN), liver function tests, and uric acid levels should be monitored periodically. Your doctor will determine the appropriate monitoring schedule based on your individual response to treatment.
References
- European Medicines Agency (EMA). Hydroxycarbamide – Summary of Product Characteristics. Available at: www.ema.europa.eu. Accessed January 2026.
- World Health Organization (WHO). WHO Model List of Essential Medicines, 23rd List (2023). Geneva: World Health Organization; 2023.
- U.S. Food and Drug Administration (FDA). Hydrea (hydroxyurea) – Prescribing Information. Available at: www.accessdata.fda.gov. Accessed January 2026.
- British National Formulary (BNF). Hydroxycarbamide – Drug Monograph. Available at: bnf.nice.org.uk. Accessed January 2026.
- National Comprehensive Cancer Network (NCCN). Clinical Practice Guidelines in Oncology: Chronic Myeloid Leukemia. Version 2.2025.
- Charache S, et al. Effect of hydroxyurea on the frequency of painful crises in sickle cell anemia. N Engl J Med. 1995;332(20):1317-1322. doi:10.1056/NEJM199505183322001
- Cortelazzo S, et al. Hydroxyurea for patients with essential thrombocythemia and a high risk of thrombosis. N Engl J Med. 1995;332(17):1132-1136. doi:10.1056/NEJM199504273321704
- Harrison CN, et al. Hydroxyurea compared with anagrelide in high-risk essential thrombocythemia. N Engl J Med. 2005;353(1):33-45. doi:10.1056/NEJMoa043800
- Ware RE, et al. Hydroxycarbamide versus chronic transfusion for maintenance of transcranial doppler flow velocities in children with sickle cell anaemia – TCD With Transfusions Changing to Hydroxyurea (TWiTCH): a multicentre, open-label, phase 3, non-inferiority trial. Lancet. 2016;387(10019):661-670. doi:10.1016/S0140-6736(15)01041-7
- Barbui T, et al. Philadelphia chromosome-negative classical myeloproliferative neoplasms: revised management recommendations from European LeukemiaNet. Leukemia. 2018;32(5):1057-1069. doi:10.1038/s41375-018-0077-1
Editorial Team
This article has been written and medically reviewed by the iMedic Medical Editorial Team, comprising specialist physicians in oncology, hematology, and clinical pharmacology. All content is based on current international guidelines and peer-reviewed research.
All medical information has been reviewed by board-certified oncologists and hematologists following the GRADE evidence framework and international treatment guidelines from WHO, EMA, and FDA.
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